On Sept. 11 , 1857, a group of Mormons formed a militia with local Indians called the Nauvoo Legion to stop a wagon train invading their land. Pretending to be friends with the Indians they later turned against them and killed them all in a massacre.

The militia, officially called the Nauvoo Legion, was composed of Utah's Mormon settlers (members of The Church of Jesus Christ of Latter-day Saints or LDS Church). Intending to give the appearance of Native American aggression, their plan was to arm some Southern Paiute Native Americans and persuade them to join with a larger party of their own militiamen—disguised as Native Americans—in an attack. During the militia's first assault on the wagon train, the emigrants fought back and a five-day siege ensued. Eventually fear spread among the militia's leaders that some emigrants had caught sight of white men and had likely discovered the identity of their attackers. As a result militia commander William H. Dame ordered his forces to kill the emigrants.
By this time the emigrants were running low on water and provisions, and allowed some approaching members of the militia—who carried a white flag—to enter their camp. The militia members assured the emigrants their protection and escorted them from the hasty fortification. After walking a distance from the camp, the militiamen, with the help of auxiliary forces hiding nearby, attacked the emigrants. Intending to leave no witnesses and thus prevent reprisals, the perpetrators killed all the adults and older children (totaling about 120 men, women, and children). Seventeen children, all younger than seven, were spared.